Dozens of politicians have split from South Korea's ruling party over the corruption scandal involving impeached president Park Geun-hye.
Their move on Tuesday could shape presidential elections that might take place in just months.
The 29 anti-Park MPs who left the Saenuri Party plan to create a new conservative party that observers say might try to recruit Ban Ki-moon, the outgoing UN secretary-general, as its presidential candidate.
There is a possibility of more MPs leaving Saenuri in coming weeks over rifts with Park loyalists who continue to occupy the party's leadership.
Choung Byoung-gug, who left Saenuri, accused the loyalists of "neglecting the values of real conservatism" and "shamelessly defending the infringement of constitutional values" as they continued to support the scandal-hit president.
"One could have seen this coming given that the presidential impeachment motion pushed through by the national assembly which happened on December 9 was backed by 234 of the lawmakers here," said Al Jazeera's Craig Leeson, reporting from Seoul.
"Fifty-six were against out of 300 which suggests that many of Park's own party members crossed the floor to make that motion go through."
|Tuesday's split could shape presidential elections that might take place in just months [EPA]
The split came as investigators widened their inquiry into the scandal surrounding Park, who has been accused of colluding with a longtime confidante to extort money and favours from the country's biggest companies, and allowing the friend to manipulate government affairs.
The team led by special prosecutor Park Young-soo was planning to summon the president's jailed friend, Choi Soon-sil, on Tuesday afternoon, following their first interrogation of her on Saturday.
PHOTOS: Seoul impeachment protests
The outgoing UN chief is seen as the best hope for conservatives to win back the Blue House after Park's collapse complicated politics for her party.
Recent opinion polls put Ban slightly ahead of liberal politician Moon Jae-in, who conceded the presidential race to Park four years ago, as the favourite to win a presidential vote.
In a recent meeting with South Korean reporters in New York, Ban said he was ready to "burn" his body in devotion for South Korea, his strongest hint yet that he would run for president.
South Korea's opposition-controlled parliament voted on December 9 to impeach Park over the scandal that drew millions of protesters in recent weeks.
Source: Al Jazeera and news agencies